No vias for filters. Not sure I've seen that on any other ST motherboard revision before.

(Has there been a Shifter can on that at all? Seems to have the mounts but cleanly removed if so)

Chip revisions seems to be the same as on my REV.B - but this is surely an earlier revision since they added loads of filters in between those two versions. If I were to guess at the date stamp on the REV.B, it's 10 1985 so only two months difference.

Yeah compare this motherboard with all the other ST(M) revisions posted on this board. Many many differences, not just the filters. Also the coil by the power connector. No "motherboard cap" near RAM etc.

duh: Scrap that about 2B before B - it's the only non-C070243 motherboard posted even!

This one doesn't have the CSYNC patch for non -M versions. Very interesting revision this

No, it does not have a composite sync.
It works well with a monochrome monitor SM124 but not SCART with SC1425: the screen is out of sync.
I found an article of ST Magazine (in French) of October 1986 which speaks about it: